In conventional prior art four-stroke internal combustion engines, the mutual angular relationships of the crankshaft and the opening and closing of the combustion valves are mechanically fixed; that is, the valves are opened and closed fully and identically with every two revolutions of the crankshaft by a camshaft rotationally driven by the crankshaft with an axis of rotation parallel to the axis of rotation of the crankshaft. In engine operation, a fuel/air mixture is drawn into each cylinder in a predetermined sequence, the mixture is ignited by the sparking plug, and the burned residue is discharged.
It is known that for much of the operating life of a multiple-cylinder engine, the load can be met by a functionally smaller engine having fewer firing cylinders, and that at times of low demand, fuel efficiency can be improved if one or more cylinders of a larger engine are withdrawn from firing service. It is known in the art to accomplish this by de-activating the valve trains leading to pre-selected cylinders (for example, one bank of intake and exhaust valves in a V-style engine) in any of various ways, such as by providing deactivating hydraulic valve lifters (DHVLs), deactivating roller finger followers (DRFFs), or deactivating hydraulic lash adjusters (DHLAs) which may be switched on and off electrically or hydraulically. (As used hereinafter, SVDD should be taken to mean generically any switchable valve deactivating device.)
It is known in the prior art to controllably distribute oil to SVDDs to operate the SVDDs via a hydraulic manifold mounted to the top of the engine block and connected to an oil riser in the engine block. Such a manifold is known in the art as a Lifter Oil Manifold Assembly (LOMA). A typical LOMA is disclosed in U.S. Pat. No. 6,817,325, issued Nov. 16, 2004, which is incorporated herein by reference.
Current technology in the automotive industry utilizes separately mounted Oil Control Valves (OCVs) in a manifold device. In the assembly of this device, all OCVs are linked and wired, to a single connector via a rigid wiring harness typically called a lead frame. Such a lead frame may be an overmolded set of wires forming a rigid harness. Rivets are typically used to attach the OCV terminals to the lead frame terminals. In other cases the OCV terminals may be welded to the lead frame terminals. In the prior art, the lead frame is a separate component in the LOMA and requires separate components and processes for attachment to a valve plate cover, which is undesirable from an economical point of view.
What is needed in the art is a LOMA that includes a decreased number of components, enables a simplified assembly process, and provides a positive connection from the OCVs to the electrical circuit.
It is a principal object of the present invention to provide a valve plate cover with an integral lead frame and an integral electrical connector and, therefore, an improved LOMA for controlling the hydraulic locking and unlocking of hydraulically-switched deactivating devices in an internal combustion engine.
It is a further object of the invention to simplify the assembly and to reduce assembly costs of an internal combustion engine having variable valve activation via a plurality of SVDDs.